Boring bar micrometer tool



Feb. 24, 1953 K. KAEHLERT BORING BAR MICROMETER Toor.

Filed May 8, 1951 KURT KAEHL ERT INVENTOR.

@my A 7'7' /VEYS Patented Feb. 24, 1953 UNITED STATES PATENT OFFICE BORING BAR MIcRoME'rEn 'roOL Kurt Kaehlert, Springfield, N. J.`

Application May s, 1951, serial No. 225,183

3 Claims.

This invention deals with boring bars, and more particularly with a boring bar having a tool bit directly connected to a micrometer screw.

Boring bars, of course, are old in the art. In recent years boring heads have been available with micrometer offset screws located in the head, such adjustments being intended to eliminate the need for oiset boring bars. However, as far as is known, there has not been available a boring bar having a micrometer adjustment for the bit along the axis of the bar, in spite of the need for such a tool.

In long boring operations with a conventional boring bar, the micrometer for measuring the linear projection of the tool from the head along the axis of the bar is located on the head. Due to the tension on the bar and the angular displacement caused by the pressure of the tool on the work, the readings obtained are not accurate, and it is necessary to pull the bar out of the work and thus obtain an accurate micrometer reading.

The device of the present invention comprises a micrometer screw directly connected in a linear manner to the cutting tool or bit. Hence, since the micrometer is on the tool itself, direct accurate micrometer readings are possible.

The invention may be more readily understood by reference to the accompanying drawing in which Figure 1 is a side view, mostly in cross-sec tion of the cutting tool and the indicator turning knob used to effect the micro movement of the bit. A rear end view of the tool, showing the micrometer scale, is depicted in Figure 2, while Figure 3 illustrates the front or bit end of the tool.

Similar numbers refer to similar parts in the various figures.

Referring again to the drawing, numeral I represents a metal barrel having interna1 bore 2 in which rides bit holder 3. Bore 2 may be circular, square, or any other shape, although a circular bore is preferred. When a circular bore 2 is employed, its periphery is provided with longitudinal groove 33 in which is inserted projecting key 8. The outside surface of bit holder 3 is also provided with a corresponding keyway or groove 34 in which rides key 8, thus preventing axial rotation of holder 3.

The rear portion 5 of bit holder 3 is turned down and threaded to engage inside threads 1 of follower 6 which likewise rides in bore 2 and is provided with longitudinal keyway 31 to prevent rotation of said follower in the bore. The rearward end of follower 6 has a smaller inside thread 38 for engaging the thread on micrometer screw I8. End 9 may be of the clutch or split screw 2. engaging type on which rides threaded washer I 0 which keeps together the clutch portions.

Micrometer screw I8 terminates at its rearward end with anchored head I4 from which projects anchoring iin 3S disposed between two floating washers I6 and I1, one of the washers being recessed to allow a loose fit for rotation of iin 3B therebetween.

Forward washer I1 rests onshoulder 39 cut into bore 2 which serves to limit forward motion of screwhead I4 into bore 2. A wider threaded opening II is provided in bore 2 to receive cap I2 having central opening I 5 in which rides sciewhead I4. Engaging end I9 of screwhead I4 is of such size as to allow slipping thereover of tube 28 attached to turning knob 3|. Crosspiece 29 in tube 28 engages the slot in end I9 and thus allows turning of screwhead I4 and, in turn, micrometer screw I3. Indicator 30 is provided on tube 28 to indicate the position of screwhead I4 with respect to scale 32 on cap I 2..

The outer surface of barrel I may be provided with center holes or stops 22 which may be accurately spaced (say every 12N) along the barrel.

These stops are used to lock barrel I in place in head 23 by means of lockscrew 24, and also allow successive forward projection of the barrel and tool for an accurate linear distance. It is apparent from the drawings that barrel I is reversible in holder 23, i. e. in Figure 1, bit 4 may be disposed either to the right of holder 23 or to the left, aS the occasion demands. Bit holder 3 may also be locked in place by set screw 20 which rests on flat portion 35. The outside of barrel I may also be provided with longitudinal groove 2l in which rides set screw 26 in head 23 and carrying key 21. Threaded holes 25 in head 23 (which is of conventional design) are used for engagement with the boring bar.

In using the present device, it is customary rst to do the rough boring with a standard tool bit which can be inserted in head 23. Thereafter, for the nal boring operation, the standard tool bit is replaced with the device of the present in vention, locking screw 24 in the desired stop 22. Then screw 20 is loosened t0 free bit holder 3, and bit 4 is adjusted to the desired amount of cut by turning micrometer screwhead I9 by means of turning knob 3|. When the adjustment is completed, screw 20 is used to lock bit holder 3 in place, and the boring operation is continued, each succeeding cut being adjusted similarly after setting the bit depth by means of scale 32. 'When screwhead I9 is turned, n 36 prevents any forward movement, so that micrometer screw I8 causes follower 6 to advance or recede, as desired, which, in turn, carries with it bit holder 3 and bit 4. Follower 6 allows independent turnin?,r of bit holder 3 so that grooves or slots 31 and 34 will be in line with each other.

It will be observed that the device of the present invention is a relatively simple, time-saving and inexpensive tool of extremely high accuracy. It may be used either as a fly boring tool or tail stock baniand can'als'ofbe employed for external cutting operations, suchas inturning shoulder anges. Also, it facilitates getting into diicult boring positions not accessible to conventional boring tools. Besides these advantages, italso has a larger tool boring range. It is particularly advantageous in tail stock operationsinvolvingz boring of back faces.

In back boring operations, for example, where` the boring bar must be moved through thegcasting or machine part, and,` the job is to be bored either with; af fly., tool V.or withthe ,help of the ,tail

stock, the` conventionalhoring. head. cannotbe usedin. most cases. On the other hand, the deviceof the'.preserltinvention,` vafter takingftheA plaoeofthe roughing tool bit, can give the operator;from.there.on, a micrometer control of the boring'tool to--obtain the. desired size. Furthermore, since the present micrometer tool bit is-incorporatedlinto a single. unit, it movable from one=holder. or adapterr to anothengiving analmost uniimitedfrangeiof boring in finishingoperations'. Thusgthefpresent tool should prove timesaving not. only in.. horizontal ori vertical.. boring, kmialsoin milling machinesand the like.

Iclaima Vl;r A completely' cylindricalboringf barmicrometen-tool, reversible ixr its holderf'and employing, lmicrometer'screw witha head projecting fromv the"l end:` off the-tool, said head: having anfengaging endlfor engaging an indicator vsleeve which indicates its position on a stationary scale disposed around the periphery of said head, comprising, in combination, a cylindrical barrel, an axial bore in said barrel, a bit holder carrying a bit on its forward end and disposed in nonrotating relation in said bore, a follower` riding in said bore in non-rotating rel-ation thereto behind said bit holder and independently attached thereto, screw engaging means on the rearward portion of said follower for engaging-a micrometer screw, and a micrometer screw heldin said screw engaging means and extending into said bore from said head.

2A, boring'bar micrometer tool according to claim 1 having a stationary cap in the end of said' barrel and in which the engaging head of thev screwheadl rotates, a scale on said cap adjacent said'engaging head, a sleeve engaging said engaginghead for turning same, and an indicator projecting from said sleeve to indicate the position of. the micrometer screw `with respect tothe scale.

3. A boring bar micrometer tooiaccording to claimllinwhchythe outside of the barrel has a longitudinalV seriesof accurately spaced center holesfinwhichsaid tool maybe held during Athe boringoperation.

KURT KAEHLERT.

REFERENCES' CITED' The following references are` of record in the.

le of this patent:

UNITEDYSTATES PATENTS 

